Method for operating a refrigeration system with heat pump function for a motor vehicle based on the refrigerant mass flow and refrigeration system with control unit for carrying out the method

Abstract

A method operating a refrigeration system with a heat pump function for a motor vehicle with an at least partially electric drive. The refrigeration system has a refrigerant compressor; a first heat exchanger; at least one further heat exchanger; a sensor device arranged upstream of the refrigerant compressor on the low-pressure side for detecting a first refrigerant pressure and/or a first refrigerant temperature; a sensor device arranged downstream of the refrigerant compressor on the high-pressure side for detecting a second refrigerant pressure and/or a second refrigerant temperature. The method includes detecting the first refrigerant pressure and/or the first refrigerant temperature; detecting the second refrigerant pressure and/or the second refrigerant temperature; detecting a rotational speed of the refrigerant compressor; determining a refrigerant volumetric efficiency; and determining a refrigerant mass flow based on the refrigerant volumetric efficiency.

1 . A method for operating a refrigeration system with heat pump function for a motor vehicle with at least partially electric drive, wherein the refrigeration system comprises:
 a refrigerant compressor,   a first heat exchanger, in particular a gas cooler or condenser;   at least one further heat exchanger, in particular an evaporator and/or a chiller and/or a heating register;   a sensor device arranged on the low-pressure side upstream of the refrigerant compressor for detecting a first refrigerant pressure and/or a first refrigerant temperature;   a sensor device arranged on the high-pressure side downstream of the refrigerant compressor for detecting a second refrigerant pressure and/or a second refrigerant temperature, the method comprising the following steps:   detecting the first refrigerant pressure and/or the first refrigerant temperature;   detecting the second refrigerant pressure and/or the second refrigerant temperature;   detecting a speed of the refrigerant compressor;   determining a refrigerant volumetric efficiency based on the pressure ratio of the first refrigerant pressure and the second refrigerant pressure and the speed of the refrigerant compressor;   determining a refrigerant mass flow based on the refrigerant volumetric efficiency.   
     
     
         2 . The method according to  claim 1 , further comprising:
 determining a low-pressure side density of the refrigerant in a superheated region based on the second refrigerant pressure and the second refrigerant temperature.   
     
     
         3 . The method according to  claim 1 , further comprising:
 determining a low-pressure side density of the refrigerant in a wet vapor region based on the second refrigerant pressure.   
     
     
         4 . The method according to  claim 1 , wherein an assigned maximum refrigerant mass flow is used for each operating state of the refrigeration system, in particular cooling operation, heating operation, reheat operation, and the speed of the refrigerant compressor in the respective operating state is limited depending on the assigned maximum refrigerant mass flow. 
     
     
         5 . A refrigeration system having heat pump function for a motor vehicle with at least partially electric drive, wherein the refrigeration system comprises:
 a refrigerant compressor,   a first heat exchanger, in particular a gas cooler or condenser;   at least one further heat exchanger, in particular an evaporator or/and a chiller or/and a heating register;   a sensor device arranged on the low-pressure side upstream of the refrigerant compressor for detecting a first refrigerant pressure and/or a first refrigerant temperature;   a sensor device arranged on the high-pressure side downstream of the refrigerant compressor for detecting a second refrigerant pressure and/or a second refrigerant temperature; and   a control unit configured to carry out the method according to  claim 1 .   
     
     
         6 . The method according to  claim 2 , further comprising:
 determining a low-pressure side density of the refrigerant in a wet vapor region based on the second refrigerant pressure.   
     
     
         7 . The method according to  claim 2 , wherein an assigned maximum refrigerant mass flow is used for each operating state of the refrigeration system, in particular cooling operation, heating operation, reheat operation, and the speed of the refrigerant compressor in the respective operating state is limited depending on the assigned maximum refrigerant mass flow. 
     
     
         8 . The method according to  claim 3 , wherein an assigned maximum refrigerant mass flow is used for each operating state of the refrigeration system, in particular cooling operation, heating operation, reheat operation, and the speed of the refrigerant compressor in the respective operating state is limited depending on the assigned maximum refrigerant mass flow.